Ribbed collector for cooling klystrons



Sept. 17, 1963 R. s. SYMONS 3,104,333

RIBBED COLLECTOR FOR COOLING KLYSTRONS Filed July 27, 1960 United StatesPatent 3,104,338 RIBBED CQLLECTOR FOR COGLING KLYSTRONS Robert S.Symons, Menlo Park, Caiifi, assigncr to Varian Associates, Palo Alto,Calif., a corporation of Calirornla Filed June 27, 1969, Ser. No. 39,168Claims. (Cl. 313-24) This invention relates in general to electron tubeappar-atus and, more particularly, to a novel cooling system of the typeemployed in cooling the electron collector of electron beam typemicrowave tubes as, for example, high power klystron tubes or travelingwave tubes.

In the art of high frequency electron beam tubes, extremely high powersare being developed; for example, high power klystron tubes in a rangeof 0.400 to 0.450 kilomegacycles are now in use which produce peakoutput powers of 125 megawatts and average power outputs of 75kilowatts. With this great amount of power output it can be readily seenthat the amount of heat to be dissipated becomes more than substantial.Cooling systems become increasingly important in order to prevent theelectrons which bombard the collector from rapidly burning through thecollector and letting the tube down to atmospheric air pressure.

Accordingly, it is the object of this invention to provide a novelcooling system for the collector of a high power electron beam tube as,for example, a high power klystron.

One feature of the present invention is the use of a large number ofcoolant channels formed in the exterior of the collector wall anddefining therebetween cooling fins of approximately equal height andwidth, and with coolant being forced through the channels to maintainuniform eflicient cooling throughout the entire collector.

Another feature of the present invention is the method of providing theoptimum amount of coolant to metal contact around the finned collectorby making the coolant channels of a width less than the width of thefins, whereby flow of heat from the collector to the coolant fluid isfacilitated.

Another feature of the present invention is the provision of an array ofradially directed narrow cool-ant channels on the end closing wall ofthe collector for efiicient cooling of the collector end wall and todecrease the mass of the end wall of the collector.

Other features and advantages of this invention will become apparentfrom a. perusal of the specification taken in connection with theaccompanying drawings wherein:

FIG. 1 is an isometric view partially broken way showing the coolantchannels for flowing cooling fluid around the collector,

FIG. 2 is a foreshortened cross-sectional view of the structure of FIG.1 taken along line 2-2 in the direction of the arrows, and

FIG. 3 is a fragmentary cross-sectional enlarged view of the collectorassembly of FIG. 2 taken along line 3--3 in the direction of the arrows.

Referring now to the figures, the collector and novel cooling system ofthe present invention comprise a hollow open ended cylindrical collector11 as of, for example, copper closed at one end by collector cone 12 asof, for example, copper which snugly fits as by brazing into a shoulder11 cut into the closed end of cylindrical collector 11. Formed as bymachining into the exterior of cylindrical collector 11 and cone 12 area large number of narrow, deep parallel and longitudinally directedchannels =13 which for-m therebetween a number of short, thick fins 13of approximate equal depth and width extending most of the length of thecollector 11 and cone 12. Closely fitting over the fins 13, as by ashrink fit for example, is a hollow, open ended cylindrical battle 14 ofBid-4,338 Patented Sept. 17, 1963 a material having a low thermalconductivity for example, stainless steel which is lower than thethermal conductivity of the collector fins 13'. The battle 14 isslightly spaced away from the open end of collector 11 and defines alongitudinally partitioned inner coolant annulus formed by the coolantchannels 13. Surrounding baffle 14 is an outer wall jacket 16 formed bya hollow, open ended cylinder having an interior diameter slightlylarger than the exterior diameter of bafile 14 and forming, with thebaflie 14, an annular outer coolant annulus. Closely fitted betweenouter wall jacket 16 and the ope-n end of collector 11 is a ring 17,which serves to support one end of outer wall jacket 11 and to reversedirection of fluid flow.

Carried at the closed end of jacket 16 is a manifold 18 which is sealedwith an 'O-ring 24- into the inner diameter of housing 16 and withO-ring 25 into the inner diameter of baflle 14. Manifold 18 as of, forexample, bronze, distributes and collects fluid for the system andconsists of a cast outer cylinder 19 closed off at one end and havingtwo apertures therein. Within outer cylinder 19 is a cast, funnel-likedistributor member 15, the tube 21 of the funnel being welded into theentrant aperture 22 of the closed end of outer cylinder 19. The spacebetween distributor member 15 and outer cylinder 19 serves as the fluidcollector for the system with the other aperture 23 of the closed end ofcylinder 19 providing an exit for the manifold 18. Both apertures 22 and23 are fitted with quick disconnect adaptors (not shown).

During operation the fluid, normal-1y water, is fed through aperture 22through tube 21 into the coolant distributor 15. The apex of collectorcone 12 acts as a separator for the water which then flows into thechannels '13 in the exterior wall of the collector cone and therealongthrough the channels in the exterior of collector 11. The width anddepth of the tins defined by channels 13 are approximately equal indimension. The maximum'waterto-metal surface is utilized so that coolingis evenly distributed over the entire collector. The fluid passesthrough the channels 13 towards the open end of the collector where thewater collector ring 17 directs the water around the end of baflie 14-:and back through the outer jacket 16 and baflle 14 and thence intowater collector 18 and out through the exit aperture 23.

It is noted that making the size of the fins deeper will not affectbetter cooling because of the rapid temperature drop along the length ofthe fin while making them wider would decrease the fluid to metalsurface area. It is clear therefore that an optimum geometry exists whenthe fins are approximately equal in depth and width.

The radial array of narrow cooling channels on the exterior surface ofthe conical end closing member or wall 12 of the collector 11efficiently removes the heat generated on the end wall .12 of thecollector permitting the mass of the end wall 12 of the collector to beminimized.

It is further noted that whether the fluid enters into aperture 22 andout aperture 23 as shown with arrows. in the drawings is a matter ofchoice and may be reversed.

Stainless steel is used in the baflle 14 between the inner and outerwater annulus because of its poor thermal conductivity. This preventsheating of the incoming fluid by outlet fluid.

Since many changes could be made in the above conruction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

'1. A collector for dissipating the energy of a high velocity beam ofcharged particles including, a tubular collector electrode for receivingthe beam incident thereon, a plurality of cooling fins defined by aplurality of peripherally spaced apart longitudinally directed channelson the exterior surface of said collector, a tubular baflle surroundingsaid cooling fins whereby said channels, said fins and said bafiledefine an interior longitudinally partitioned annulus, said tubularbaflle being made of a material having a thermal conductivity less thanthe thermal conductivity of said fins, a tubular outer jacketsurrounding said bathe and spaced apart therefrom whereby said bathe andsaid outer jacket define an exterior annulus and means communicatingwith said interior and exterior annulus for distributing an input and anoutput flow of coolant therethrough.

2. A collector for dissipating the energy of a high velocity beam ofcharged particles including, a tubular collector terminated by aninwardly conve-nging end portion, a plurality of cooling fins ofapproximately equal width and depth, said cooling fins defined by deep,narrow, longitudinally running channels on the exterior surface of saidcollector, said tubular bafiie being made of a material having a thermalconductivity less than the thermal conductivity of the material of saidfins, a tubular balfie surrounding said cooling fins whereby an interiorannulus is defined by said channels and bafile, said tubular bafilebeing made of material having a low thermal conductivity, a tubularouter jacket surrounding said bafile and spaced apart therefrom wherebyan exterior annulus is defined by said baflle and said outer jacket, amanifold for distributing an input and output flow of cooling fluid forsaid interior and exterior annulus, said manifold including a hollowtubular outer distributor closed at one end, said outer distributorbeing apertured to provide a coolant inlet and outlet, the open end ofsaid outer distributor mating with the outer jacket of said exteriorannulus, an inner distributor means communicating with an aperture insaid outer jacket at one end and surrounding the converging end portionof said collector and mating with the bafile of said interior annulus atthe other end, and means for supplying and receiving coolant through theapertures in said outer distributor.

3. A cooling collector for dissipating energy of a high velocity beam ofcharged particles including, a tubular collector electrode for receivingthe beam incident thereon, a plurality of cooling fins of approximatelyequal depth and width, said cooling fins defined by a plurality ofperipherally spaced apart longitudinally directed channels on theexterior sun-face of said collector, a tubular baffie surrounding saidcooling fins whereby said channels, said fins and said bafile define aninterior, longitudinally partitioned annulus, a tubular outer jacketsurrounding said bafile and spaced apart therefrom whereby said baflleand said outer jacket define an exterior annulus, said tubular bafilebeing made of a material having a thermal conductivity less than thethermal conductivity of the material of said fins, and meanscommunicating with said interior and exterior annulus for distributingan input and output 4 flow of coolant therethrough, said baflle of lowerthermal conductivity acting to prevent a heat exchange between saidoutput and input flow of coolant.

4. The collector according to claim 1 wherein the width of saidlongitudinally directed channels is less than the width of said coolingfins.

5. The collector according to claim 3 wherein the width of saidlongitudinally directed channels is less than the width of said coolingfins.

6. A collector for dissipating the energy of a high velocity beam ofcharged particles including, a tubular collector member for receivingthe beam on the interior surfaces thereof, an array of longitudinallydirected-peripherally spaced apart cooling fins provided on the exteriorsurface of said tubular collector member, said fins defining betweenthem an array of peripherally spaced apart longitudinally directedcoolant channels extending lengthwise of said tubular collector memberin a contin nous manner over a preponderance of the, length of saidtubular collector member, a member surrounding said fins and channelswhereby said fins, channels andsaid member define a first longitudinallypartitioned cooling annulus, an end wall closing said tubular collector,an array of peripherally spaced apart elongated cooling channelsprovided on the exterior surface of said end wall and' radiating outfrom the center of said end wall and defining therebetween a pluralityof cooling fins, a member covering over said fins and channels on saidend wall and defininga second cooling annulus, said second coolingannulus being in fluid communication with said first cooling annulus,and distributor means communicating with said first and second coolingannuli for distributing input and output flow of fluid coolant to saidcollector under pressure.

7. The collector according to claim 6 wherein saidlon- V gitudinallydirected fins on said tubular collector member are of approximatelyequal depth and width.

8. The collector according to claim 6 wherein said i coolant channels onsaid tubular collector member have a' width less than the width of saidcooling fins on said tubular collector member.

9. The collector according to claim 6 wherein the coolant channels onsaid tubular collector member and said end closing wall have a widthless than the width of said cooling fins on said tubular collectormember and said end closing wall.

10. The collector according to claim'6 whereinsaid end closing wall is ahollow generally cone-like structure.

References Cited in the file of this patent

1. A COLLECTOR FOR DISSIPATING THE ENERGY OF A HIGH VELOCITY BEAM OFCHARGED PARTICLES INCLUDING, A TUBULAR COLLECTOR ELECTRODE FOR RECEIVINGTHE BEAM INCIDENT THEREON, A PLURALITY OF COOLING FINS DEFINED BY APLURALITY OF PERIPHERALLY SPACED APART LONGITUDINALLY DIRECTED CHANNELSON THE EXTERIOR SURFACE OF SAID COLLECTOR, A TUBULAR BAFFLE SURROUNDINGSAID COOLING FINS WHEREBY SAID CHANNELS, SAID FINS AND SAID BAFFLEDEFINE AN INTERIOR LONGITUDINALLY PARTITIONED ANNULUS, SAID TUBULARBAFFLE BEING MADE OF A MATERIAL HAVING A THERMAL CONDUCTIVITY LESS THANTHE THERMAL CONDUCTIVITY OF SAID FINS, A TUBULAR OUTER JACKETSURROUNDING SAID BAFFLE AND SPACED APART THEREFROM WHEREBY SAID BAFFLEAND SAID OUTER JACKET DEFINE AN EXTERIOR ANNULUS AND MEANS COMMUNICATINGWITH SAID INTERIOR AND EXTERIOR ANNULUS FOR DISTRIBUTING AN INPUT AND ANOUTPUT FLOW OF COOLANT THERETHROUGH.